Seek further evidence, including mechanistic studies and confirmatory trials of benefits and potential harms in advanced trauma systems

Haemorrhage is the principal cause of 30-40% of all trauma deaths, and half of these occur before admission to hospital.1 Many bleeding patients develop coagulopathy, making control of haemorrhage more difficult. In some patients this coagulopathy develops early2 and seems to be associated with excessive fibrinolysis and breakdown of clots.3 Current protocols for massive transfusions of blood products (variably defined as >10 red cell units or >50% blood volume in 24 hours, or >5 units in four hours) to patients with haemorrhagic shock prescribe plasma and cryoprecipitate to replace lost, consumed, diluted, or dysfunctional clotting factors, but these do not specifically treat fibrinolysis. There is now compelling evidence that tranexamic acid (1 g loading dose plus 1 g over eight hours), a relatively safe and inexpensive antifibrinolytic, should be administered within three hours of injury in patients at risk of severe bleeding.

The evidence for change

Tranexamic acid was discovered in the 1950s and has been used during surgery to minimise blood loss. A systematic review evaluated 126 randomised controlled trials in elective surgery and three in emergency surgery (total of 10 488 patients) that had been conducted between 1972 and 2011. This showed that tranexamic acid reduced blood transfusions by a third (risk ratio 0.62, 95% confidence interval 0.58 to 0.65),4 an effect that persisted when only trials with adequate allocation concealment were considered (0.68, 0.62 to 0.74). In these higher quality trials the effect on mortality was uncertain (0.67, 0.33 to 1.34), as was …